The discussion below is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
An aspect of the present invention relates to genetic modification of moderately thermophilic Bacillus strains to provide the capability to utilise sucrose to Bacillus strains originally not possessing this capability.
Moderately thermophilic Bacillus species, preferably those species that are facultative anaerobic and homolactic, are ideal organisms for the industrial manufacture of lactic acid.
In an aspect of this invention, moderately thermophilic Bacillus species are capable of growing between 37 and 65° C. and allow industrial fermentation at temperatures above 50° C. This high fermentation temperature has several advantages when fermenting on industrial scale: less risk of infections and thus higher product purity, faster reactions etcetera. Furthermore, the nutrient requirements of these bacteria are less demanding than those of lactic acid bacteria such as Lactobacillus species, which also allows for relatively inexpensive industrial processes.
Moderately thermophilic Bacillus species include aerobic species and facultative anaerobic species. The use of facultative anaerobic species is preferred, since these species allow fermentation under anaerobic conditions, or at least under a low partial pressure of oxygen, which for industrial scale is desirable. Such conditions prevent demand for costly aeration and enable the use of low-cost media, while minimizing contamination risks or even allowing non-sterile production procedures.
It is also preferred to use moderately thermophilic Bacillus species that are homolactic. The homolactic nature allows the production of lactic acid from hydrocarbon sources (including hexose and pentose sugars) without the formation of more than 15 wt % side products such as formic acid and acetic acid. Genetic modification of the homolactic phenotype can be applied to convert homolactic strains into homofermentative production strains for other industrial products derivable from glycolysis, such as from phosphoenolpyruvate and/or pyruvate. Examples of these compounds are pyruvate, acetolactate, diacetyl, acetoin, 2,3-butanediol, 1,2-propanediol, acetate, formate, acetaldehyde, ethanol, L-alanine, oxaloacetate, S-malate, succinate, fumarate, 2-oxoglutarate, oxalosuccinate, isocitrate, citrate, glyoxylate.
Preferably these production strains are sporulation deficient.
Examples of moderately thermophilic and facultative anaerobic Bacillus species are Bacillus coagulans, Bacillus smithii, Bacillus thermoamylovorans and Bacillus thermocloacae, at least the first two species also being homolactic. A preferred species is Bacillus coagulans. 
It is desirable in industrial fermentations to use cheap raw materials in the fermentation media. For instance, sucrose or sucrose-containing substrates are often used as low-cost carbon sources for industrial fermentations. However, it was found that not all moderately thermophilic Bacillus strains used for industrial fermentations possess the capability to utilise sucrose as a carbon source. This is a disadvantage, especially if such strains have undergone adaptations to improve their fermentation capability or production potential on an industrial scale. For instance, Bacillus coagulans strain DSM 1 appeared to be a very poor fermenter of sucrose. Only scarce growth and acid formation is observed using sucrose as sole carbon source, which is probably due to non-specific activity of systems for utilisation of other sugars.
In literature, B. coagulans is mentioned to be variable in sucrose utilisation capability (De Clerck, E., M. Rodriguez-Diaz, G. Forsyth, L. Lebbe, N. Logan, 2004: Polyphasic characterization of Bacillus coagulans strains. Syst. Appl. Microbiol. 27:50-60). However there is no information available on genes involved in sucrose catabolism and there are no genes annotated for sucrose catabolism in the B. coagulans 36D1 genome sequence.